This U.S. patent application Ser. No. 09/903,152, filed Jul. 11, 2001, claims priority to and is a continuation application of PCT application PCT/CH 00/00017, filed Jan. 11, 2000, which claims priority to German patent application DE 19900792.6, filed Jan. 12, 1999 and issuing Jun. 15, 2000 as German Patent DE 199 00 792 Cl.
1. Field of the Invention
The invention relates to a device for administering an injectable product, as set forth in the preamble of claim 1.
2. Description of Related Art
An injection device, such as the invention also relates to, is known from WO 97/36625. The injection device comprises: a casing; a product reservoir with a piston movably accommodated therein, which when moved in a feed direction forces product out of the reservoir; a drive means; and a dosing means.
The drive means comprises a drive member which can be moved along a sliding axis up to a proximal end position in the feed direction and up to a distal end position counter to the feed direction, and a driven member which is prevented from moving counter to the feed direction, but which is slaved by the drive member when the drive member is moved in the feed direction, so moving the piston in the feed direction such that product is forced out of the reservoir. When setting the path length which the driven member covers in one complete stroke, and thus the product dosage to be delivered, the drive member is moved counter to the feed direction and relative to the driven member back to its distal end position. The distal end position is set by means of a dosing means, while the proximal end position is defined by a stopper on the casing.
The dosing means comprises the drive member and the dosing member for setting the distal end position of the drive member. The dosing member is positioned in the casing and may be rotated about the sliding axis of the drive member. It comprises a dosage stopper encircling the sliding axis in the form of a spiral, which the drive member abuts if moved to the distal position, i.e. the distal position of the drive member is determined by the rotational angular position of the dosing member.
The product dosage to be delivered is selected by rotating the dosing member in discrete steps. For this purpose, the dosing member locks in rotational angular locking positions provided at regular intervals between the casing and the dosing member. Rotating the dosing member between two adjacent blocking positions corresponds to the smallest adjustable product dosage. The spirally encircling dosage stopper of the dosing member exhibits a discontinuous course. It drops in discrete steps from a most proximal section to its most distal section. A dosage cam radially projecting from the drive member is provided thereon as a dosage counter stopper which, when the drive member is moved back for dosing, is moved up against the section of the dosage stopper of the dosing member which lies opposite the cam due to the rotation of the dosing member. The dosage cam of the drive member is very slim in this construction.
It is an object of the invention to provide a device, particularly of the above kind, for administering an injectable product, said device exhibiting a high mechanical strength as regards the components used for product dosage, wherein the dosage precision and accuracy of previously known devices is at least maintained.
The invention concerns a device for the dosed administering of an injectable product, comprising:
a) a casing, comprising a reservoir for the product;
b) a piston, forcing product out of the reservoir when moved in a feed direction towards a reservoir outlet;
c) a drive member, which may be moved along a sliding axis in the feed direction up to a proximal end position, and against the feed direction up to a distal end position;
d) a driven member, which is prevented from moving against the feed direction, and is slaved by the drive member when the drive member is moved in the feed direction, so moving the piston in the feed direction;
e) a dosing member, which may be rotated about the sliding axis of the drive member, to set the product dosage to be administered;
f) wherein in the distal end position, the drive member and the dosing member abut via at least one dosage stopper each, one of which is provided on the drive member and the other on the dosing member, the drive member and the dosing member preferably abutting each other via said stoppers; and wherein
g) at least one of these dosage stoppers at least partially encircles the sliding axis of the drive member in the form of a spiral.
According to the invention, said at least one spiral dosage stopper exhibits a continuous course and a constant pitch relative to the sliding axis of the drive member.
Although the spiral dosage stopper does not essentially have to entirely encircle the sliding axis, a spiral dosage stopper which does is preferred. The spiral dosage stopper is preferably provided on the dosing member, and a cooperating dosage counter stopper on the drive member. However, this arrangement can essentially also be reversed.
Damage to the spiral dosage stopper cannot be caused by moving the drive member back too forcefully. In particular, the danger of causing damage to the spiral dosage stopper is reduced by the omittance of edges. Furthermore, the spiral dosage stopper makes the manufacture of the preferably injection-molded plastic parts simpler. Dosage can also be made more precise, since a minimum necessary angular spacing between adjacent, discretely determined or determinable rotational angular positions of the dosing member is at best still preferably determined by means provided for determining these rotational angular positions, such means preferably being formed between the dosing member and the casing of the device by locking means of a locking mechanism.
According to the invention, the dosage counter stopper, preferably formed on the drive member, may be of a width which, measured perpendicular to the feed direction, is larger than a distance, measured in the rotational direction, between two immediately consecutive rotational angular positions of the dosing member. In other words, the angle which the dosage counter stopper covers to the spiral dosage stopper may be larger than the angle between two immediately consecutive, determined or determinable rotational angular positions of the dosing member. It is especially preferred that the width of the dosage counter stopper is at least twice the angular spacing between two immediately consecutive rotational angular positions of the dosing member. The dosage counter stopper can be made considerably broader, perpendicular to the feed direction, while still maintaining the same precision and accuracy of dosage as in, for example, the injection device from WO 97/36625. At most, it may be formed running completely around the sliding axis. Preferably, however, its angle of extension does not exceed ten times that of the aforementioned angular spacing.
The drive member and dosing member are preferably arranged such that the one is surrounded by the other. Correspondingly, the two dosage stoppers cooperating during dosage, namely that of the drive member and that of the dosing member, may be provided on the opposing surface areas facing each other on the drive member and dosing member. Preferably, the dosing member concentrically surrounds a distal area of the drive member. In accordance with a preferred example embodiment of this design, the spiral dosage stopper of the dosing member is formed by the proximal front face of the dosing member, and the dosage stopper of the drive member is formed by a dosage cam projecting from the outer surface of the drive member, perpendicular to the feed direction.